Switch contact and method of manufacture



B. LGOLBECK ETAL swITcH CONTACT AND mmnon OF MANUFACTURE {Filed Sept. 8. 1957 2 Sheets-Sheet L ql (I Q Q Q OSOIO O O O O on mm U W. I

INVENTORS. BERNARD J. GOLBECK RAYMOND F. LEWANDOWSKI BY fl fi u-w, Wig 4, M444 {Wrw ATTORNEYS.

Oct. 6, 1970 B. J. GOLBECK ET 3,531,861

SWITCH CONTACT AND METHOD OF MANUFACTURE 2 Sheets-Sheet 2 Filed Sept. 8. 1967 United States Patent O M U.S. Cl. 29-622 1 Claim ABSTRACT OF THE DISCLOSURE A method of manufacture of a double Wipe stator clip contact for a switch comprising the steps of providing an elongated strip of fine-grain sheet metal, partially cutting the blank of a stator clip with its two legs extending at right angles to the longitudinal axis of the strip and With an uncut strip of material forming a supporting web between adjacent legs of the clip blanks, forming a resilient arch and contact jaw in each leg of the clip, severing one of the webs between two adjacent legs of adjacent clip blanks, folding oneof the two legs over the other, severing the remaining web between the adjacent clip blanks and mounting the formed clips on a switch stator in an automatic assembly operation. The

strip of sheet material has thereon a narrow longitudinal band of precious metal corresponding with the contact surfaces of the stator clip blanks.

BACKGROUND OF THE INVENTION Heretofore, double wipe stator clips for switches were cut from a long strip of metal with their length running in the same direction as the length of the strip such that the folded arch of the clip leaf was disposed 90 to the strip length. This caused any flexing of the clip leaf to be 90 to the elongated crystalline structure of the material since the crystalline structure or grain of the material ran in the same direction as the material length. It has been found that by utilizing ultra fine-grain material, which effectively has no grain direction, the clips can be cut out of the elongated strip of metal in any direction desired. In accordance with the method of this invention, clips are fabricated at right angles to the length of the elongated strip of metal and thereby afford easy automatic assembly on switch stators. The method facilitates automatic formation with a minimum of tooling; and results in a greater yield of clips, in a ratio of approximately 2:1, over methods heretofore used, with a corresponding reduction of scrap. The formed clips may be left joined in a continuous strip for automatic assembly.

The methods heretofore used employed multislide presses which comprise cam operated plungers arranged in series to perform successive operations on automatically fed stock. However, many different sizes of clips are required in the manufacture of diflerent switches and the changeover of a multislide machine for a different clip is a tedious operation requiring several hours. In carrying out the method of this invention, punch presses are employed with a progressive die, requiring the setup of only a single part. A number of operations with a single tool (such as a combined pierce and cutoff die) can be performed and thereby reduce costs. Progressive punch press dies require only a few minutes to set up and also effect savings in material and in wear upon the die parts.

SUMMARY OF THE INVENTION An object of this invention is to provide a new and improved method of manufacture of a double wipe stator clip contact for a switch.

3,531,861 Patented Oct. 6, 1970 Another object is to provide such a method which permits forming the stator clip at right angles to an elongated strip of sheet material.

A further object is to provide a method of manufacturing stator clips resulting in a greater number of clips formed per square inch of material and reducing the amount of scrap.

Still another object is to provide such a method which permits the use of an elongated strip of sheet material having a narrow band of precious metal corresponding with the contact surfaces of the stator blanks running longitudinally of the metal strip.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a strip of sheet material illustrating various steps of constructing a double Wipe stator clip contact embodying the invention;

FIG. 2 is a sectional view taken generally along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken generally along the line 33 of FIG. 1;

FIG. 4 is a sectional view taken generally along the line 4-4 of FIG. 1;

FIG. 4A is a view similar to that of FIG. 4, showing a longer form of stator clip contact;

FIG. 5 is a partial plan view of a switch stator with stator clip contacts, embodying the invention, mounted thereon;

FIG. 6 is a sectional view taken generally along the line 66 of FIG. 5; and

FIG. 7 is a schematic view of various machines as correlated With strips of sheet material to illustrate the various steps of forming a stator clip contact, embodying the invention, and mounting the stator clips on a switch stator in an automatic assembly operation.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the invention, a plurality of stator contacts are constructed in strip form from which finished contact clips are thereafter severed. The various steps involved in the construction of the contact clips are conveniently carried out by means of various machines and by various combined operations performed simultaneously at different stations on a strip of material that is fed through the machines, whereby the clip is blanked, formed, cut off and fed to an eyeletting machine for automatic assembly on a switch stator, all of which will be more fully described below.

Referring particularly to FIGS. 1 and 7, a double wipe stator clip contact is formed from an elongated strip 10 of fine-grain sheet metal, preferably brass, having a maximum grain size of the order of 0.015 millimeter. The strip of metal is fed through a blanking machine or station 12 (FIG. 7) Where the strip is punched with mounting holes 14 which subsequently receive an eyelet or rivet 15 (FIG. 6) for mounting the clip to a stator. At machine 12, terminal receiving apertures 16 are punched in the metal strip. Teardrop-shaped apertures 17, if desired, may also be punched at station 12 for purposes to be hereinafter described.

Referring to FIG. 1, the width of the strip may also be reduced as at 18, depending upon the desired length of the finished clip. At machine 12, the elongated strip is also partially cut, as at 20 in FIG. 1, to form two legs 22 extending at right angles to the longitudinal axis of the metal strip leaving portions 24a, 24b of uncut strip material defining supporting webs between the legs 22 of adjacent clip blanks. The strip is rerollcd and transferred to a cutoff and forming machine or station 26, FIG. 7.

Normally, strip 10 will be inlayed with a narrow band of precious metal, such as silver, brazed along the area of contact surfaces 28 (FIG. 1) of the stator clip blanks.

Alternatively, the entire strip may. beplated with the precious metal before or preferably after the blanking or punching steps are performed. The area of contact surfaces 28 may be selectively plated after blanking. At station 12, after the above blanking steps are performed, a contact jaw 30 is formed on the outer extremities of each leg of the clip blank and one of the supporting webs (for instance, 24a in FIG. 1) is severed. The strip is then fed to a forming and eyeletting machine 31 (FIG. 7).

Referring to FIGS. 4 and 4A, the stator clip contact is provided with a resilient arched portion, generally designated 32, intermediate the ends of legs 22 with teardrop-shaped apertures 17 disposed in the arched portions. This can be done at the same time the contact jaws 30 are formed The teardrop-shaped apertures 17 are provided with their wider portions extending toward the contact surfaces 28 of the clips to increase the resiliency of the clips and permit the clips to function at a much lower stress than clips heretofore available as the clips flex between mounting rivets and the contact surfaces 28,

The blanking machine 12 preferably comprises a punch press with a progressive die which may incorporate a number of the above-mentioned operations in a single tool. For instance, at the blanking machine a single die may combine several successive operations such as punching the holes 14, apertures 16 and 17, and forming the legs 22 by cuts 20, and/or a single tool may be provided to sever the web 2411 and form the resilient arches 32 and contact jaws in a progressive operation by a single progressive die. i

At the forming and eyeletting machine 31, one of the two legs of the clip blank is folded over the other, as at 33 (FIGS. 1 and 4), the remaining supporting web 24b is severed and the separate clips are fed to an eyeletting portion 35 of machine 31. The clips are then positioned and the machine is programmed to eyelet the clips automatically to a switch stator 38. The stators are contained in a magazine for feeding to an eyeletting position, generally designated 42, where the stator is automatically indexed or rotated by a preset program for successive eyeletting of the stator clips to the stator.

FIG. 7 illustrates that two sizes of clips (FIGS. 4 and 4A) may be formed on opposite sides of machine 31 and simultaneously fed thereto. Referring to FIG. 5, most rotary switches have at least one long contact clip, generally designated 46, which constantly engages a rotary contact ring 48, while a protruding tab 48a on ring 48 selectively engages the shorter contact clips as the ring is rotated. The blanking machine 12, to the right in FIG. 7, would perform similar operations as performed by machine 12 but would fabricate longer clips 46 by the same steps as referred to above in regard to the shorter clips.

The terminal end of the clips may be formed by bending away from the stator as at 50 (FIG. 6) individually as the clips are assembled to stator 38 or all the clips may be formed at one time after assembly to the stator.

Alternatelythe clips may be left flat or bent back over the outer periphery of the stator, as shown in phantom in FIG. 6. However, bend may be formed at machine 31 prior to severing web 24b. Folds 33 are preferably formed on a radius of the order of at least twice the thickness of the strip to provide a resilient loop which permits slight relative longitudinal movement of the two legs of the clips as the terminal ends are bent, as at 50, and thereby prevent buckling of the legs.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art.

We claim:

1. The method of progressively and successively forming double wide stator clip contacts from elongated strip stock which has a width at least the unfolded length of each said clip and successively assembling formed clips to a statorswitch insulator support comprising the successive steps of: punching progressively and successively pairs of mounting holes, each pair being transversely aligned with the longitudinal axis of said strip and spaced therealong a distance greater than the width of each clip and each hole spaced from its respective lateral edge of the strip to leave contact jaw material thereat; punching progressively and successively pairs of slots each between the respective hole and lateral edge of said strip and in transverse alignment with said holes for defining the internal configuration of each jaw; removing progressively and successively material between the material defining said slots and said holes to define the substantial external shape of each clip leaving two interconnecting webs each spaced laterally inwardly from the said jaw material portion of each clip; shaping progressively said contact jaw material at the lateral extent of each clip; severing progressively and successively one web and folding on said longitudinal axis the clip to align a pair of said holes and thereby juxtapose said jaws into operating relation; cutting progressively and successively the remaining web of each folded clip for separating it from said strip; and progressively and successively securing each folded and separated clip to said support with a mounting element extending through a pair of aligned said holes.

References Cited UNITED STATES PATENTS 2,273,099 2/1942 Gilbert 113-119 XR 2,571,040 10/1951 Juvinal et al.

2,727,299 12/ 1955 Klumpp 113-119 XR 3,209,110 9/1965 Meyer.

3,213,211 10/ 1965 Allison.

3,288,949 11/1966 Brown.

3,309,178 3/1967 Klumpp et al. 113-119 JOHN F. CAMPBELL, Primary Examiner R. W. CHURCH, Assistant Examiner U.S. Cl. X.R. 

